基于回溯法的排课设计

根据我校的排课实际情况,应用回溯法,在Visual C++6.0平台上开发排课系统,系统实现课程信息的设置、排课约束条件的设置、系统管理、排课结果显示、排课优化等功能.实验表明,回溯法与随机因子相结合的方法应用于排课系统,能快速得到排课结果,提高回溯法的效率,系统通过排课优化提高排课结果的满意度.     

概率论中几个重要概念的教学探析

对概率论中几个重要的概念如随机事件、随机变易和概率密度等进行解读,并且对求解概率密度函数之原理和一个条件较弱的概率密度变换公式加以证明。     

Random quadralinear forms and schur product on tensors

In this work, we made progress on the problem that lr(○×)lp(○×)lq is a Banach algebra under schur product. Our results extend Tonge's results. We also obtained estimates for the norm of the random quadralinear form A:lMr×lNp×lKq×lHs→ C, defined by: A(ei, ej, ek, es)=aijks, where the (aijks)'s are uniformly bounded, independent, mean zero random variables. We proved that under some conditions lr(○×)lp(○×)lq (○×)ls is not a Banach algebra under schur product.     

Statistics and Intuition for the Classroom

Examples and case studies are presented of statistical reasoning, thinking and intuition that may arise in perception of randomness and in particular for random walks. The relationship between art and science can be explored through various notions of the statistical concepts of randomness.     

Bachelor’s degree student dropouts: Who tend to stay and who tend to leave?

Factors of students’ dropout can be studied either by surveys among students or by analyzing data the university collects. In the work reported in this paper, we analyzed data known about students at the time of admission as well as data about the students' study achievements collected on a semester basis. Using data about students who enrolled in the academic year 2013/14, we created several data mining models to predict who will finish their studies successfully and who will not. Our results show that the key factor is the percentage of lost credit vouchers in the most recent semester. The pre-entry attributes have only a very small impact. We also created association rules of different types to find characteristics of students who did not successfully complete the first semester of study. Here, the factor that mainly increases the probability of a failure is the time gap between secondary and tertiary education.     

The Unrelenting Exchange Paradox

An elusive probability paradox is analysed. The fallacy is traced back to improper use of a symbol that denotes at the same time a random variable and two different values that it may assume.     

Reliability based multiobjective optimization for design of structures subject to random vibrations

Based on a multiobjective approach whose objective function （OF） vector collects stochastic reliability performance and structural cost indices, a structural optimization criterion for mechanical systems subject to random vibrations is presented for supporting engineer＇s design. This criterion differs from the most commonly used conventional optimum design criterion for random vibrating structure, which is based on minimizing displacement or acceleration variance of main structure responses, without considering explicitly required performances against failure. The proposed criterion can properly take into account the design-reliability required performances, and it becomes a more efficient support for structural engineering decision making. The multiobjective optimum （MOO） design of a tuned mass damper （TMD） has been developed in a typical seismic design problem, to control structural vibration induced on a multi-storey building structure excited by nonstationary base acceleration random process A numerical example for a three-storey building is developed and a sensitivity analysis is carried out. The results are shown in a useful manner for TMD design decision support.     

GSM-MRF based classification approach for real-time moving object detection

Statistical and contextual information are typically used to detect moving regions in image sequences for a fixed camera. In this paper, we propose a fast and stable linear discriminant approach based on Gaussian Single Model （GSM） and Markov Random Field （MRF）, The performance of GSM is analyzed first, and then two main improvements corresponding to the drawbacks of GSM are proposed： the latest filtered data based update scheme of the background model and the linear classification judgment rule based on spatial-temporal feature specified by MRF. Experimental results show that the proposed method runs more rapidly and accurately when compared with other methods.     

我国区域生态环境效率时空特征及影响因素分析

在以消耗大量不可再生资源为代价的经济发展模式下,我国生态环境不断恶化,严峻的生态环境已经成为当下社会经济发展的重大阻碍之一。本文运用三阶段DEA模型对我国2008—2017年各省市及各区域生态环境效率进行了时空对比研究。结果表明,(1)三阶段DEA模型较传统DEA更加合理,在不考虑外部环境因素和随机因素的影响下,会使生态环境效率真实值明显高估。(2)不同的环境变量对于生态环境效率的影响作用不同,人口密度、城市化水平有利于提升各省市的环境效率水平；人均GDP和外贸依存度会对环境效率产生负面影响,第二产业增加占比在不同阶段对不同投入变量则体现出不同特征。(3)调整后的区域间真实生态环境效率水平存在明显的空间不平衡现象,华东、东北地区生态环境效率值较高,西南、西北地区处于较低水平。(4)各省市受纯技术效率和规模效率的影响在地域上有较大差异,如西南、西北地区规模效率在第一阶段被明显高估,华南、华中地区则是纯技术效率被高估。针对各省市及各地区表现出来的不同特征,提出各省市应根据研究结果对症下药,充分考虑外部环境因素,合理调整经济、做到经济与环境保护协调发展的对策建议。